1. Field of the Invention
The present invention relates generally to the field of environmental monitoring. More specifically the present invention relates to an automated water testing apparatus and to a method of using the apparatus to test the amounts of dissolved salts and other solids in a water sample to meet the requirements of the Clean Water Act, found at 40 C.F.R. 136 and the Safe Drinking Water Act, found at 40 C.F.R. 141. The apparatus includes a specially constructed sample bottle which preferably has a flexible wall and is fitted with a screw-on removable filter cap having a mesh top wall through which sample water can be poured to remove suspended matter including organics and plant matter, at least one and preferably several receiving vessels preferably in the form of beakers, and a desiccator enclosure. The apparatus further includes a computer containing a database and an inventive computer program for executing most or all of the method, and several devices designed to be connected to the computer so that they are controlled by and relay data to the computer such as through a two-way bus. These devices preferably include a conductivity meter having a meter electrode, a robotic arm having a gripper, an analytical scale, a top loader balance scale and an oven.
The method, in summarized form, includes but is not limited to the steps of: providing the above apparatus; one of a person and the computer through operation of the robotic arm delivering a sample of water to be tested into the sample bottle and securing the filter cap onto the bottle; the computer operating the robotic arm to lift and place the conductivity meter electrode into the sample water and activating the conductivity meter to perform a test to determine the concentration of salt in the sample water; the computer operating the robotic arm gripper to grasp the bottle, to hold it over at least one and preferably sequentially over several receiving vessels such as a beakers, and to tilt the bottle to a sufficient angle from vertical and for a sufficient duration to pour a selected quantity of sample water through the filter cap and into each beaker; and the computer operating the gripper of the robotic arm to squeeze the plastic sample bottle at least one time to force water otherwise obstructed by suspended matter through the filter cap sequentially into each beaker; the computer operating the robotic arm to cause the gripper placing the beakers one at a time onto the scale; the scale automatically relaying to the database and recording the weight of each successive beaker and the water it contains, and the program subtracting the known tare weight of each beaker to determine the water sample weight within each beaker, until at least two successive weights of each given beaker match; placing the beakers into the oven between weighings; the computer operating the robotic arm to cause the robotic arm to place the beaker into the oven; the computer causing the oven to activate and heat the beakers to a first temperature for a first period of time until the water in the beakers is fully evaporated, leaving only solid residue from the sample water in each of the beakers, which may include a substantial quantity of salt; the computer operating the robotic arm to remove the beakers from the oven and to place them one at a time on the scale; the scale relaying the beaker and solids residue weight to the computer such that the weight data is stored in the database; the computer program calculating the ratio of solids to water by weight and displaying, storing and printing the ratio such as in milligrams per liter or in parts per million (ppm). The results of this total dissolved solids (TDS) test reveal whether the water sample meets EPA requirements of a maximum of 500 mg per liter for drinking water.
The squeeze force applied by the gripper to squeeze the sample bottle preferably is in a range of 1 to 7 pounds. Squeeze force at the higher end of this range is applied where there is a high concentration of suspended matter in the sample water, causing flow resistance through the filter cap mesh. The amount of squeezing is not determined by displacement. In pouring sample water into each beaker, the computer detects the weight of the beaker on the scale in real time, such that the computer knows when the given beaker has received the desired quantity of sample water whereupon the computer causes the robotic arm and gripper to stop pouring from the sample bottle.
Applicant has discovered that a suitable robotic arm that is produced by ST ROBOTICS™. Yet applicant found that the gripper provided with this robotic arm is not suitable for performing steps of the present invention, and therefore found it necessary to replace it with a different gripper made by another manufacturer, ROBOTIQ™ of Canada, for another purpose. The ROBOTIQ™ gripper is intended for gripping eggs. This gripper has an intuitively variable gripping and squeezing force and provides variable opening and closing speed. The grippers of other known robotic arms simply open and close with a fixed force and at a fixed speed. The several devices designed to be connected to the present computer can both read and write, incorporating a two-way bus. Each device sends data signals back to the computer and the computer sends signals to the device to control its operation.
Key inventive features include the squeezable sample bottle with the filter cap, the use of a robotic arm and gripper for tilting and squeezing the bottle, which is made possible by the use of the inventive bottle filter, preferably embodied in the filter cap, the synergy of the combination of these apparatus elements, the method steps, and the program itself which executes much of the inventive method.
2. Description of the Prior Art
There has long been water testing equipment and procedures for using the equipment.
Nakamura, et al, U.S. Pat. No. 5,306,087, issued on Apr. 26, 1994, discloses an apparatus for thermogravimetry. Nakamura, et al., provides a computer operated robotic arm which lifts sample containers on and off a thermobalance which weighs the containers empty and then full, and then subtracts the container weight. The steps performed, however, are not intended to meet and fall short of what is required for testing according to the above mentioned water quality Acts, such as conductivity testing to determine salt content and filtration to remove suspended solids and organics.
Razulis, U.S. Pat. No. 4,125,376, issued on Nov. 14, 1978, teaches a method for detecting water pollutants through the use of a sampling test tube containing a foam cube impregnated with a detection chemical solution. Once again, this method and apparatus fall far short of meeting the requirements of the Acts, as do the following prior patents. Tonge, et al., U.S. Patent Application Publication Number 2002/0092362, published on Jul. 17, 2002, reveals a flow-metering and sampling catch basin insert, providing means for isolating water entering a catch basin or manhole from flows from other catch basins so that the flow rate and water quality for water entering the catch basin can be measured without contamination. Las Navas Garcia, U.S. Pat. No. 7,172,729, issued on Feb. 6, 2007 discloses a mixed sample moisture or ash analyzer which uses a robotic arm to retrieve a crucible from a conveyor and to insert the crucible into a small opening in an upper wall of a furnace, placing it on a carousel inside the furnace. This patent does not address the requirements of water quality analysis. Finally, Pang, et al., U.S. Pat. No. 8,038,942, issued on Oct. 18, 2011, teaches an automated sample processing system involving the handling of biological specimen containers such as to perform centrifugation and decapping.
It is thus an object of the present invention to provide a water testing apparatus and method of using the apparatus which is largely or entirely automated to an extent that unattended operation is achieved and human operators are no longer necessary.
It is another object of the present invention to provide such a method which is largely or wholly executed by a computer and produces reliable results and meets government standards and requirements.
It is still another object of the present invention to provide such an apparatus includes an inventive sample bottle with a filter cap and makes new use of a robotic arm with a gripper, making such automation possible.
It is yet another object of the present invention to provide such an apparatus and method which employee use with only minimal training.
It is finally an object of the present invention to provide such an apparatus which provides greater precision with greater quality and which is safe and inexpensive enough to be practical.